WATCH: Circa Survive Unplugs, Covers Nirvana

Their just-released, SPIN-approved third album, Blue Sky Noise, has them on the verge of stardom -- and afforded them their biggest commercial success to date, with a No. 11 debut on the album charts -- but Philly's Circa Survive aren't all muscular riffage and throbbing rhythms, as they proved with a four-song acoustic set at SPIN's NYC office. Watch the video below!

Stopping by on the street date of Blue Sky Noise, the quintet turned in delicately-composed, stripped-down versions of three songs from the new album: lead single "Get Out" (hear the album version here), album opener "Strange Terrain," and the thunderous "Imaginary Enemy."

But these recordings showcase a completely different angle of the nuanced interplay between guitarists Brandon Ekstrom and Colin Frangicetto, and an alternate vocal approach from singer Anthony Green, who reels in his trademark falsetto for a grittier sound.

A special bonus: Circa played a faithful cover of Nirvana's In Utero gem "Dumb" -- the band played an entire set of Nirvana covers at last month's Hoodwink fest in California.

Watch the videos and tell us what you think in the comments section. And, to hear about how Circa Survive got their name, check out their "Name That Band" feature.